Reaction valve device for tractortrailer brake operation



J. RODWAY May 25, l1948.

REACTION VALVE DEVICE FOR TRACTOR-TRAILER BRAKE OPERATION 5 Sheets-Sheet1 Filed Nov. 25, 1944 Inventor May 25', 1948- J. RoDwAY `vr2,442,020

REACTION VALVE DEVICE FOR TRACTOR-TRALER BRAKE OPERATION Filed Nov. 25,1944 5 sheets-sheet 2 4 @Inventor A ltorneys May 25, 1948- l J. RDWAY2,442,020

REACTION VALVE DEVICE FOR TRACTOR-TRAILER BRAKE OPERATION venlo!" B 2 yc; Lm

Patented May 25, 1948 nEAcrIoN'vALvE nevica Foa macrommmeamxn OPERATIONY V.lohn Rodway, Lincoln; England Application November 25, 1'94'4;Serial Nor-'565,157 vIn Great-Britain October 4,-,1943

(Cl. 18S-3) 4 Claims.

This invention relates to 'means for controlling the brakes on trailervehicles and thefrear portions of articulated vehicles andlnasfor itsobject to provide an improved construction ori arrange'- ment of amechanical character designed to avoid unnecessary complication on thetractor vehicle and tofprovlde for a graduated brake applicationproportional to the effort applied.

The invention is applicable 'to brake operation by" vacuum or'pressure"a-ct'uateciY means and` is capable of mechanical adaptationrto suit-therequirements ofi vehicles ofi vary-ingr types.y

According tothe inventionia device for controlling the operation ofthebrakesona trailer vehicle or the like-is providedy wherein pressure'applied to a pedal istransmittedf-througn ai system of levers movableabout a common pivotl to a valve whose openingfcau'ses the 'applicationof differential vii'uid pressure 'to a' ibrake cylinder or' cylinderswith-a' lforce proportional tothe pedal effort', such lforce being also*applied through means for-ming part ofthe li'lalve actuating mechanlsmto a reactionV :lever included -insald lever system.

Accordi-ngy to the preferredfform of the invention a device for`controlling theoperationof the brakes on a trailer vehicle'or'thelike`'comprises a valve adapted to Vcontrol the'- ap'plica'ftion of vacuumor pressure lfiuid tol brake actuating mechanism, a pedal actuated rod,vlevers" fzifiov'-` able in 4miposi-te directon'sabouta common -pivot,one of said levers" having aconnectionto sai-d pedal actuated rod and'Aa-lost'-motion=connec tion to meansy for actuating fsa'idf valveandar-ii other 'of said leversv being movable about av lined pivot atone end and having a' connectiontoan output rodat the opposite end.

nReferencewill nowy yben'iade' to the 'accom' panying drawings whichillustrate avvacuuin re action valve' according" to the" invention andvin which- Fig. 1 is a .longitudinal sectional elevation showing theinoperative position;

Fig, 2 is a' cross-'section'takenonftheline v-A-=B of Fig. 1,

Fig. 3 is a plan of Fig. land y Fig, 4 is a sectional elevation similarto Fig. 1 but showing an operative position.

The'reaction valve illustrated in the drawings isadapted to beinterposed between a bralceoperatin'g pedal andacross shaft' on atractor ve'- hicle through whichvw movement' li'sltransmittef to themechanism for applying the tractor brakes. A pedal operated rodindicated at I is connected to a fork 2 connected toa reaction lever 3mounted at its upper endrover av sleeve 4-iwhic-hsurh rounds,v `loutisof substantially greater. internal diameter thanffa pinSowhichrlscar-ried inaseeondffork vt in tum connected,A through avrod tothe cross shaft onv the tractor vehicle. Passing through the reactionleverisapivotpin-l about whichare also movable 4twofouter ,levers whichact" together andare l xed-around-L t'he pinv 5 at their upperends and..around av iixedf` pin 9 at their-.lower ends. Y

The :reaction lever 3 hasealsoalostfmotion connection-.wth the ,pin- 95,the said lever being mountedat its lower end: over asleeve I0 ofsubstantially greater. internaldiameter than the diameter of` the` pin8: The--said-sleeveis-also connected-by a link H i with lthe `rod, I-2`vofv a piston 13:`

movable in `a cylinder Y. I4 lformilzig I part ofv a valvehousingl15Ebutuseparatedtherefrom bythe pistol-1V I3.

The valve housing |25 has vaport l Iiiv adaptedfto be connected to afsource f of vacuumfand a sec ond port 1 adaptedftobe connected totheconven-tional brake cylinders--onthe trailer vehicle. The porti I6communicates with .a passage VI8 withinV thenvalve r housing l5 whoseinner end y is adaptedl tobc closedf-bya valve member i Si whichengagesftheend of atubulan seatingv 20- formingthe inner 4extremity of:thepassage- I8. The. valve member yI 9- is-normally urged into vitsclosed. posi tion by a `spring- ZIr-acting -upon al disc 22'-- which issecured-centrally tothevalve member,- both disc and valve beingrnovablyl mounted within a valve cham-berl 2-3^forfmed within anextension 2410i piston I3, whichy extension surrounds the tubular Valveseating 20-and terminates in an inwardly directed annular 4flange' 2'5constituting a valve member, whichv is* adapted to.engage thev valvemember I9 as hereinafter described.

Thepistcn I3 isfnormally urged i to the position shown; in` Fig;llibyazsprng 26 whose Aouter en'd ybears against thez-cndgwallvo. thecylinder I4.

and-.thepistonr is; formed'lwit-ha- -portgor passage 2llwhichenables-1:communieationsV to be `estab--v lishedbetweenthevcylinder M andfthevalve'hous i ing'. `'ZIhef-fhousing; `l5has'anfextensonz in :which the ends offthezpin arezmountedand.theextemsionhas a 'slot' 294 on its upper side' through :which thelevers y3l and.8 frproiect and .which limitsv the extent of pivotal movementof thesaid levers.

The-operation of.y thedevice above described is zas-follows:

Duringy the initial movement yof thebrake actuating pedal, the pivot pin'I is held against movement by the cross shaft return springs, and,therefore, Iduring the initial movement, the reactionlever 3 is movedabout the pin 'I to the extent ber I9 and seals the valvehousingagainstgin-J gress'of air and secondlyunseats the Valve inemberI9 so that suction is exerted through passages I6, I8 and 2i) to placetheinterior Yof the valve on the trailer vehicle.

,l housing under vacuum which is ,also exerted through port I1 and thebrake operating cylinders i' Y l' iiiuidlpressure to the brake cylinderwith a pres-V sureproportional to the pedal eiort, said system Duringthe initial stage oi. brakev operation, the -r pins 4 and 1 remainstationary so that the lever` 3 is moved out of alignment Withth`e'levers 8 Y i@ owing to the pivotal movement of lever Sabout the pin'I and the parts of the device are in the positions shown in Fig. 4

The vacuum exerted'in the valve housing I5, thereafter, tends tomovevthe piston I3 towards the left and re-seat thevalvemember I9 sothat theforce required to reopenthe valve member I9 vwillbecomeigreater-as the vacuum in the housing ake cylinders on the l5 andthe'conventional br trailer Vehicle increases.

Y Any increase of vacuum in the valve housing I5 tends; by returning thevalve member I 9 to closing position, to oppose the separation ofthelevers 3 and Sgin the manner shownV in Fig. 4 and the movement thusimparted tothe reaction lever 3 is transmitted to the pedal so that theoperator can feell' the increase in braking pressure.

The `force applied by the brake operating pedal acting about the lengtha of the reaction lever 3 is balanced bythe reaction of'valve piston I3act- Ving about the length b of the reaction'lever. Dur? Ving brakeapplication, the pull transmitted to the brake cross shaft from the fork6 thus remains exactlythesame value as if it were connected directly tothe pedal and the only effect ofthe valve on the pedal is that theclearances atthe upper and lowerV ends ofthe reaction lever cause a veryslight lost motion at the pedal. As the brake applying eiort isrelaxed'the suction in the vvalve housing I5 aided by ythfe spring 26tends to restore Y the piston I 3 andthe Valve I9 to the positionsshownin Fig. l, whereinair owing through the passage 21 will reduce thedegree of vacuum in the Vvhousing I5 and also in the trailer brakecylinders in proportion to the reduced load on the fork 2.

In the event of failurefof vacuum through any cause, the brakes Von thetractor Vehicle, which may be of the usual or conventional form, will beoperated mechanically withr a slight initial lost motionY at the pedal,the levers 3 `and 8 moving around pinY 9 in anY a'nticlockwisevdirection as the pull is applied through rod I.

It is to be understood that Various modifications may be made in thedevice above described Without departing from the invention.For-example,

to apply the invention to the control of uid pres-1 sure operated brakemechanism, the position of the -valve'mernber I9 would have to berevised so that it would normally be held on its seating by pressure andmechanically unseated to allow the pressure'iiuid to operate in thevalvehousing,

such operation being arranged so as to move the piston'towards theleit.`

Theemechanical transmission' components can also be arranged to operateunder thrust instead of pull and the device can be adapted to suitvarying requirements by such variation Vas arranging the fork 6 in areverse position and connecting it to an output rod lying insubstantially the same direction as the pedal rod I. Y

I claim:

1. A device for controlling theoperation of theV Y brakes on a trailervehicle, comprising a valve for Controlling thefappncanon ofdifferential Yduid pressure to the brake cylinder, a pedal operated rod,and a system of levers for transmitting pres- A*sure applied to thepedal to said valve to. open it^ and thereby cause application ofdifferential -of leversfincluding a reaction lever connected at one endtothe rod and having means connected VVVto its` other-end for actuatingsaid valve, a iixed pivot, a sleeve connected to the rod, said reactioneating withthe brake cylinderandhavihg apas-k sage through whichdifferentialV fluid vpressure is applied tossaid Vall/e'chambenanda'piston in said valvechamber responsiveto Vthe differential fluidpressure Vin said chamber to; close the valve s and oppose operativemovement; of said reaction lever. Y

3. VA devicel according toclaim 1,f wherein said valve comprises` ahousing having a'cylinder forming a part thereof, a-piston operating vinsaid cylinder, anda valve `member carried by 'said f piston, andincluding4 a link connecting said other end of, said reaction lever tosaid'pistomsaid valve member being arranged to be unseated byopera-Vtion Vof said piston to enable Vdiierential uid pressure to be appliedtothe brake cylinder'.Y

4; Adev-ce accordingto claim 1,-wherein said valve comprises a housing`vhaving aV cylinder forming a part thereof,apiston operating inY saidcylinder, and a valve member carried bysaidpiston, and including a'linkconnecting said otherk end of said reaction lever to said piston, saidvalve memberk being arranged to be unseatedjby operationof said pistonto enable diierential iiuidy pressure to be applied to the brakecylinder, and saidsystem of -leversj comprising a pair of leversYconnected atone end .to said output memf ber and at the oppositeendtosaid xed pivot,

and said `pivot pin about which saidreaction leverV is movable ismounted in said pair of levers.r Y-

Y JOHN RODWAY,

Examinations CI'IED f The followingreferences are of record in the le ofthis patent: y Y Y' w Y n.

' UNITED sTA'TEsPATENTs@ f Number Name Date Y 1,882,411VV Doty Y oct.11,1932 1,999,456 Hickman Apr. 30, l1935V 2,111,322 Johnson Mar.. 15, 19382,232,974

Roy Feb. 25, 1 941

